Question

The surface of water in a lake appears green due to a layer of tiny free-floating organisms X on its surface. The lake water also contains organisms like water beetle, fish and tadpole. The sun shines over the lake water and provides energy for the functioning of this lake ecosystem.
(a) What could organisms X be?
(b) Write a food chain comprising of all the four organisms mentioned.
(c) What is the general name of the food chains like the one written above?
(d) Name (i) secondary consumer (ii) producer (iii) tertiary consumer, and (iv) primary consumer, in the above food chain.
(e) If the tertiary consumer gets 0.2 J of energy from the secondary consumer, then how much energy was radiated by the sun to the producer?

Answer 1

(a) X could be phytoplankton.

(b) Phytoplankton $\to$ Tadpole $\to$ Water beetle $\to$ Fish

(c) 'Aquatic food chain' is the general name of food chains such as the one described above.

(d) (i) In the given food chain, the water beetle is the secondary consumer.
(ii) The phytoplankton is the producer.
(iii) The fish is the tertiary consumer.
(iv) The tadpole is the primary consumer.

(e) Sun $\to$ Phytoplankton $\to$ Tadpole $\to$ Water beetle $\to$ Fish
20,000 J $\to$ 200 J $\to$ 20 J $\to$ 2 J $\to$ 0.2 J